Head having wrap-controlled flexible media interface

ABSTRACT

An apparatus according to one embodiment includes a module having a tape bearing surface, a magnetic transducer in a thin film region, and an edge closest to the transducer. A guide is positioned relative to the edge for inducing tenting of a moving magnetic recording tape above a tape tenting region of the tape bearing surface. The magnetic transducer is positioned along the tape tenting region. The magnetic transducer is positioned a distance from a location on the tape bearing surface directly under a peak that is more than one-fourth the length from the location directly under the peak to the edge closest thereto.

BACKGROUND

The present invention relates to data storage systems, and moreparticularly, this invention relates to magnetic data storage systems,specifically, magnetic tape heads.

In magnetic storage systems, magnetic transducers read data from andwrite data onto magnetic recording media. Data is written on themagnetic recording media by moving a magnetic recording transducer to aposition over the media where the data is to be stored. The magneticrecording transducer then generates a magnetic field, which encodes thedata into the magnetic media. Data is read from the media by similarlypositioning the magnetic read transducer and then sensing the magneticfield of the magnetic media. Read and write operations may beindependently synchronized with the movement of the media to ensure thatthe data can be read from and written to the desired location on themedia.

An important and continuing goal in the data storage industry is that ofincreasing the density of data stored on a medium. For tape storagesystems, that goal has led to increasing the track and linear bitdensity on recording tape, and decreasing the thickness of the magnetictape medium. However, the development of small footprint, higherperformance tape drive systems has created various problems in thedesign of a tape head assembly for use in such systems.

In a tape drive system, the drive moves the magnetic tape over thesurface of the tape head at high speed. Usually the tape head isdesigned to minimize the spacing between the head and the tape. Thespacing between the magnetic head and the magnetic tape is crucial andso goals in these systems are to have the recording gaps of thetransducers, which are the source of the magnetic recording flux in nearcontact with the tape to effect writing sharp transitions, and to havethe read elements in near contact with the tape to provide effectivecoupling of the magnetic field from the tape to the read elements.

SUMMARY

An apparatus according to one embodiment includes a module having a tapebearing surface, a magnetic transducer in a thin film region, and anedge closest to the transducers. A guide is positioned relative to theedge for inducing tenting of a moving magnetic recording tape above atape tenting region of the tape bearing surface. The magnetic transduceris positioned along the tape tenting region. The magnetic transducer ispositioned a distance from a location on the tape bearing surfacedirectly under a peak that is more than one-fourth the length from thelocation directly under the peak to the edge closest thereto.

An apparatus according to another embodiment includes a module having atape bearing surface, an array of magnetic transducers in a thin filmregion, and an edge closest thereto. A guide is positioned relative tothe edge for inducing tenting of a moving magnetic recording tape abovea tape tenting region of the tape bearing surface. The magnetictransducers are positioned along the tape tenting region. The magnetictransducers are positioned a distance from a location on the tapebearing surface directly under a peak that is more than one-fourth thelength from the location directly under the peak to the edge closestthereto.

A method according to yet another embodiment includes positioning aguide relative to an edge of a module having a tape bearing surface, amagnetic transducer in a thin film region, and an edge closest thereto,and, running a moving magnetic recording tape above the tape bearingsurface for inducing tenting of the moving magnetic recording tape abovea tape tenting region of the tape bearing surface. The magnetictransducer is positioned toward an edge of the tape tenting region atabout a point of closest approach of the tape and the tape bearingsurface.

Any of these embodiments may be implemented in a magnetic data storagesystem such as a tape drive system, which may include a magnetic head, adrive mechanism for passing a magnetic medium (e.g., recording tape)over the magnetic head, and a controller electrically coupled to themagnetic head.

Other aspects and embodiments of the present invention will becomeapparent from the following detailed description, which, when taken inconjunction with the drawings, illustrate by way of example theprinciples of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic diagram of a simplified tape drive systemaccording to one embodiment.

FIG. 1B is a schematic diagram of a tape cartridge according to oneembodiment.

FIG. 2 illustrates a side view of a flat-lapped, bi-directional,two-module magnetic tape head according to one embodiment.

FIG. 2A is a tape bearing surface view taken from Line 2A of FIG. 2.

FIG. 2B is a detailed view taken from Circle 2B of FIG. 2A.

FIG. 2C is a detailed view of a partial tape bearing surface of a pairof modules.

FIG. 3 is a partial tape bearing surface view of a magnetic head havinga write-read-write configuration.

FIG. 4 is a partial tape bearing surface view of a magnetic head havinga read-write-read configuration.

FIG. 5 is a side view of a magnetic tape head with three modulesaccording to one embodiment where the modules all generally lie alongabout parallel planes.

FIG. 6 is a side view of a magnetic tape head with three modules in atangent (angled) configuration.

FIGS. 7A-7C are schematics depicting the principles of tape tenting.

FIGS. 8A-8C are partial side views of a magnetic tape head according tovarious embodiments.

FIG. 8D is a partial side view of a magnetic tape head with an outriggeraccording to one embodiment.

FIG. 8E is a partial side view of a magnetic tape head with an outriggeraccording to one embodiment.

FIG. 8F is a partial side view of a magnetic tape head with magnetictape passing over the head at different wrap angles according to variousembodiments.

FIG. 9 is a partial side view of a magnetic tape head according to oneembodiment.

DETAILED DESCRIPTION

The following description is made for the purpose of illustrating thegeneral principles of the present invention and is not meant to limitthe inventive concepts claimed herein. Further, particular featuresdescribed herein can be used in combination with other describedfeatures in each of the various possible combinations and permutations.

Unless otherwise specifically defined herein, all terms are to be giventheir broadest possible interpretation including meanings implied fromthe specification as well as meanings understood by those skilled in theart and/or as defined in dictionaries, treatises, etc.

It must also be noted that, as used in the specification and theappended claims, the singular forms “a,” “an” and “the” include pluralreferents unless otherwise specified.

The following description discloses several preferred embodiments ofmagnetic storage systems, as well as operation and/or component partsthereof.

In one general embodiment, an apparatus a module having a tape bearingsurface, a magnetic transducer in a thin film region, and an edgeclosest to the transducers. A guide is positioned relative to the edgefor inducing tenting of a moving magnetic recording tape above a tapetenting region of the tape bearing surface. The magnetic transducer ispositioned along the tape tenting region.

In another general embodiment, an apparatus includes a module having atape bearing surface, an array of magnetic transducers in a thin filmregion, and an edge closest thereto. A guide is positioned relative tothe edge for inducing tenting of a moving magnetic recording tape abovea tape tenting region of the tape bearing surface. The magnetictransducers are positioned along the tape tenting region.

In yet another general embodiment, an apparatus includes a module havinga tape bearing surface, a magnetic transducer in a thin film region, andan edge closest thereto. A guide is positioned relative to the edge forinducing tenting of a moving magnetic recording tape above a tapetenting region of the tape bearing surface. The magnetic transducer ispositioned toward an edge of the tape tenting region at about a point ofclosest approach of the tape and the tape bearing surface.

FIG. 1A illustrates a simplified tape drive 100 of a tape-based datastorage system, which may be employed in the context of the presentinvention. While one specific implementation of a tape drive is shown inFIG. 1A, it should be noted that the embodiments described herein may beimplemented in the context of any type of tape drive system.

As shown, a tape supply cartridge 120 and a take-up reel 121 areprovided to support a tape 122. One or more of the reels may form partof a removable cartridge and are not necessarily part of the system 100.The tape drive, such as that illustrated in FIG. 1A, may further includedrive motor(s) to drive the tape supply cartridge 120 and the take-upreel 121 to move the tape 122 over a tape head 126 of any type. Suchhead may include an array of readers, writers, or both.

Guides 125 guide the tape 122 across the tape head 126. Such tape head126 is in turn coupled to a controller 128 via a cable 130. Thecontroller 128, may be or include a processor and/or any logic forcontrolling any subsystem of the drive 100. For example, the controller128 typically controls head functions such as servo following, datawriting, data reading, etc. The controller 128 may include at least oneservo channel and at least one data channel, each of which include dataflow processing logic configured to process and/or store information tobe written to and/or read from the tape 122. The controller 128 mayoperate under logic known in the art, as well as any logic disclosedherein, and thus may be considered as a processor for any of thedescriptions of tape drives included herein, in various embodiments. Thecontroller 128 may be coupled to a memory 136 of any known type, whichmay store instructions executable by the controller 128. Moreover, thecontroller 128 may be configured and/or programmable to perform orcontrol some or all of the methodology presented herein. Thus, thecontroller 128 may be considered to be configured to perform variousoperations by way of logic programmed into one or more chips, modules,and/or blocks; software, firmware, and/or other instructions beingavailable to one or more processors; etc., and combinations thereof.

The cable 130 may include read/write circuits to transmit data to thehead 126 to be recorded on the tape 122 and to receive data read by thehead 126 from the tape 122. An actuator 132 controls position of thehead 126 relative to the tape 122.

An interface 134 may also be provided for communication between the tapedrive 100 and a host (internal or external) to send and receive the dataand for controlling the operation of the tape drive 100 andcommunicating the status of the tape drive 100 to the host, all as willbe understood by those of skill in the art.

FIG. 1B illustrates an exemplary tape cartridge 150 according to oneembodiment. Such tape cartridge 150 may be used with a system such asthat shown in FIG. 1A. As shown, the tape cartridge 150 includes ahousing 152, a tape 122 in the housing 152, and a nonvolatile memory 156coupled to the housing 152. In some approaches, the nonvolatile memory156 may be embedded inside the housing 152, as shown in FIG. 1B. In moreapproaches, the nonvolatile memory 156 may be attached to the inside oroutside of the housing 152 without modification of the housing 152. Forexample, the nonvolatile memory may be embedded in a self-adhesive label154. In one preferred embodiment, the nonvolatile memory 156 may be aFlash memory device, ROM device, etc., embedded into or coupled to theinside or outside of the tape cartridge 150. The nonvolatile memory isaccessible by the tape drive and the tape operating software (the driversoftware), and/or another device.

By way of example, FIG. 2 illustrates a side view of a flat-lapped,bi-directional, two-module magnetic tape head 200 which may beimplemented in the context of the present invention. As shown, the headincludes a pair of bases 202, each equipped with a module 204, and fixedat a small angle α with respect to each other. The bases may be“U-beams” that are adhesively coupled together. Each module 204 includesa substrate 204A and a closure 204B with a thin film portion, commonlyreferred to as a “gap” in which the readers and/or writers 206 areformed. In use, a tape 208 is moved over the modules 204 along a media(tape) bearing surface 209 in the manner shown for reading and writingdata on the tape 208 using the readers and writers.

The substrates 204A are typically constructed of a wear resistantmaterial, such as a ceramic. The closures 204B may be made of the sameor similar ceramic as the substrates 204A.

The readers and writers may be arranged in a piggyback or mergedconfiguration. An illustrative piggybacked configuration comprises a(magnetically inductive) writer transducer on top of (or below) a(magnetically shielded) reader transducer (e.g., a magnetoresistivereader, etc.), wherein the poles of the writer and the shields of thereader are generally separated. An illustrative merged configurationcomprises one reader shield in the same physical layer as one writerpole (hence, “merged”). The readers and writers may also be arranged inan interleaved configuration. Alternatively, each array of channels maybe readers or writers only. Any of these arrays may contain one or moreservo track readers for reading servo data on the medium.

FIG. 2A illustrates the tape bearing surface 209 of one of the modules204 taken from Line 2A of FIG. 2. A representative tape 208 is shown indashed lines. The module 204 is preferably long enough to be able tosupport the tape as the head steps between data bands.

In this example, the tape 208 includes 4 to 32 data bands, e.g., with 16data bands and 17 servo tracks 210, as shown in FIG. 2A on a one-halfinch wide tape 208. The data bands are defined between servo tracks 210.Each data band may include a number of data tracks, for example 1024data tracks (not shown). During read/write operations, the readersand/or writers 206 are positioned to specific track positions within oneof the data bands. Outer readers, sometimes called servo readers, readthe servo tracks 210. The servo signals are in turn used to keep thereaders and/or writers 206 aligned with a particular set of tracksduring the read/write operations.

FIG. 2B depicts a plurality of readers and/or writers 206 formed in agap 218 on the module 204 in Circle 2B of FIG. 2A. As shown, the arrayof readers and writers 206 includes, for example, 16 writers 214, 16readers 216 and two servo readers 212, though the number of elements mayvary. Illustrative embodiments include 8, 16, 32, 40, and 64 activereaders and/or writers 206 per array, and alternatively interleaveddesigns having odd numbers of reader or writers such as 17, 25, 33, etc.An illustrative embodiment includes 32 readers per array and/or 32writers per array, where the actual number of transducer elements couldbe greater, e.g., 33, 34, etc. This allows the tape to travel moreslowly, thereby reducing speed-induced tracking and mechanicaldifficulties and/or execute fewer “wraps” to fill or read the tape.While the readers and writers may be arranged in a piggybackconfiguration as shown in FIG. 2B, the readers 216 and writers 214 mayalso be arranged in an interleaved configuration. Alternatively, eacharray of readers and/or writers 206 may be readers or writers only, andthe arrays may contain one or more servo readers 212. As noted byconsidering FIGS. 2 and 2A-B together, each module 204 may include acomplementary set of readers and/or writers 206 for such things asbi-directional reading and writing, read-while-write capability,backward compatibility, etc.

FIG. 2C shows a partial tape bearing surface view of complementarymodules of a magnetic tape head 200 according to one embodiment. In thisembodiment, each module has a plurality of read/write (R/W) pairs in apiggyback configuration formed on a common substrate 204A and anoptional electrically insulative layer 236. The writers, exemplified bythe write transducer 214 and the readers, exemplified by the readtransducer 216, are aligned parallel to an intended direction of travelof a tape medium thereacross to form an R/W pair, exemplified by the R/Wpair 222. Note that the intended direction of tape travel is sometimesreferred to herein as the direction of tape travel, and such terms maybe used interchangeably. Such direction of tape travel may be inferredfrom the design of the system, e.g., by examining the guides; observingthe actual direction of tape travel relative to the reference point;etc. Moreover, in a system operable for bi-direction reading and/orwriting, the direction of tape travel in both directions is typicallyparallel and thus both directions may be considered equivalent to eachother.

Several R/W pairs 222 may be present, such as 8, 16, 32 pairs, etc. TheR/W pairs 222 as shown are linearly aligned in a direction generallyperpendicular to a direction of tape travel thereacross. However, thepairs may also be aligned diagonally, etc. Servo readers 212 arepositioned on the outside of the array of R/W pairs, the function ofwhich is well known.

Generally, the magnetic tape medium moves in either a forward or reversedirection as indicated by arrow 220. The magnetic tape medium and headassembly 200 operate in a transducing relationship in the mannerwell-known in the art. The piggybacked MR head assembly 200 includes twothin-film modules 224 and 226 of generally identical construction.

Modules 224 and 226 are joined together with a space present betweenclosures 204B thereof (partially shown) to form a single physical unitto provide read-while-write capability by activating the writer of theleading module and reader of the trailing module aligned with the writerof the leading module parallel to the direction of tape travel relativethereto. When a module 224, 226 of a piggyback head 200 is constructed,layers are formed in the gap 218 created above an electricallyconductive substrate 204A (partially shown), e.g., of AlTiC, ingenerally the following order for the R/W pairs 222: an insulating layer236, a first shield 232 typically of an iron alloy such as NiFe (-),cobalt zirconium tantalum (CZT) or Al—Fe—Si (Sendust), a sensor 234 forsensing a data track on a magnetic medium, a second shield 238 typicallyof a nickel-iron alloy (e.g., ˜80/20 at % NiFe, also known aspermalloy), first and second writer pole tips 228, 230, and a coil (notshown). The sensor may be of any known type, including those based onMR, GMR, AMR, tunneling magnetoresistance (TMR), etc.

The first and second writer poles 228, 230 may be fabricated from highmagnetic moment materials such as ˜45/55 NiFe. Note that these materialsare provided by way of example only, and other materials may be used.Additional layers such as insulation between the shields and/or poletips and an insulation layer surrounding the sensor may be present.Illustrative materials for the insulation include alumina and otheroxides, insulative polymers, etc.

The configuration of the tape head 126 according to one embodimentincludes multiple modules, preferably three or more. In awrite-read-write (W-R-W) head, outer modules for writing flank one ormore inner modules for reading. Referring to FIG. 3, depicting a W-R-Wconfiguration, the outer modules 252, 256 each include one or morearrays of writers 260. The inner module 254 of FIG. 3 includes one ormore arrays of readers 258 in a similar configuration. Variations of amulti-module head include a R-W-R head (FIG. 4), a R-R-W head, a W-W-Rhead, etc. In yet other variations, one or more of the modules may haveread/write pairs of transducers. Moreover, more than three modules maybe present. In further approaches, two outer modules may flank two ormore inner modules, e.g., in a W-R-R-W, a R-W-W-R arrangement, etc. Forsimplicity, a W-R-W head is used primarily herein to exemplifyembodiments of the present invention. One skilled in the art apprisedwith the teachings herein will appreciate how permutations of thepresent invention would apply to configurations other than a W-R-Wconfiguration.

FIG. 5 illustrates a magnetic head 126 according to one embodiment ofthe present invention that includes first, second and third modules 302,304, 306 each having a tape bearing surface 308, 310, 312 respectively,which may be flat, contoured, etc. Note that while the term “tapebearing surface” appears to imply that the surface facing the tape 315is in physical contact with the tape bearing surface, this is notnecessarily the case. Rather, only a portion of the tape may be incontact with the tape bearing surface, constantly or intermittently,with other portions of the tape riding (or “flying”) above the tapebearing surface on a layer of air, sometimes referred to as an “airbearing”. The first module 302 will be referred to as the “leading”module as it is the first module encountered by the tape in a threemodule design for tape moving in the indicated direction. The thirdmodule 306 will be referred to as the “trailing” module. The trailingmodule follows the middle module and is the last module seen by the tapein a three module design. The leading and trailing modules 302, 306 arereferred to collectively as outer modules. Also note that the outermodules 302, 306 will alternate as leading modules, depending on thedirection of travel of the tape 315.

In one embodiment, the tape bearing surfaces 308, 310, 312 of the first,second and third modules 302, 304, 306 lie on about parallel planes(which is meant to include parallel and nearly parallel planes, e.g.,between parallel and tangential as in FIG. 6), and the tape bearingsurface 310 of the second module 304 is above the tape bearing surfaces308, 312 of the first and third modules 302, 306. As described below,this has the effect of creating the desired wrap angle relative to thetape bearing surface 310 of the second module 304.

Where the tape bearing surfaces 308, 310, 312 lie along parallel ornearly parallel yet offset planes, intuitively, the tape should peel offof the tape bearing surface 308 of the leading module 302. However, thevacuum created by the leading edge 318 of the leading module 302 hasbeen found by experimentation to be sufficient to keep the tape adheredto the tape bearing surface 308 of the leading module 302. The trailingedge 320 of the leading module 302 (the end from which the tape leavesthe leading module 302) is the approximate reference point which definesthe wrap angle of the second module 304. The tape stays in closeproximity to the tape bearing surface until close to the trailing edge320 of the leading module 302. Accordingly, read and/or write elements322 may be located near the trailing edges of the outer modules 302,306. These embodiments are particularly adapted for write-read-writeapplications.

A benefit of this and other embodiments described herein is that,because the outer modules 302, 306 are fixed at a determined offset fromthe second module 304, the inner wrap angle is fixed when the modules302, 304, 306 are coupled together or are otherwise fixed into a head.The inner wrap angle is approximately tan⁻¹(δ/W) where δ is the heightdifference between the planes of the tape bearing surfaces 308, 310 andW is the width between the opposing ends of the tape bearing surfaces308, 310. An illustrative inner wrap angle is in a range of about 0.3°to about 1.1°, though can be any angle required by the design.

Beneficially, the inner wrap angle on the side of the module 304receiving the tape (leading edge) will be larger than the inner wrapangle on the trailing edge, as the tape 315 rides above the trailingmodule 306. This difference is generally beneficial as a smaller tendsto oppose what has heretofore been a steeper exiting effective wrapangle.

Note that the tape bearing surfaces 308, 312 of the outer modules 302,306 are positioned to achieve a negative wrap angle at the trailing edge320 of the leading module 302. This is generally beneficial in helpingto reduce friction due to contact with the trailing edge 320, providedthat proper consideration is given to the location of the crowbar regionthat forms in the tape where it peels off the head. This negative wrapangle also reduces flutter and scrubbing damage to the elements on theleading module 302. Further, at the trailing module 306, the tape 315flies over the tape bearing surface 312 so there is virtually no wear onthe elements when tape is moving in this direction. Particularly, thetape 315 entrains air and so will not significantly ride on the tapebearing surface 312 of the third module 306 (some contact may occur).This is permissible, because the leading module 302 is writing while thetrailing module 306 is idle.

Writing and reading functions are performed by different modules at anygiven time. In one embodiment, the second module 304 includes aplurality of data and optional servo readers 331 and no writers. Thefirst and third modules 302, 306 include a plurality of writers 322 andno data readers, with the exception that the outer modules 302, 306 mayinclude optional servo readers. The servo readers may be used toposition the head during reading and/or writing operations. The servoreader(s) on each module are typically located towards the end of thearray of readers or writers.

By having only readers or side by side writers and servo readers in thegap between the substrate and closure, the gap length can besubstantially reduced. Typical heads have piggybacked readers andwriters, where the writer is formed above each reader. A typical gap is20-35 microns. However, irregularities on the tape may tend to droopinto the gap and create gap erosion. Thus, the smaller the gap is thebetter. The smaller gap enabled herein exhibits fewer wear relatedproblems.

In some embodiments, the second module 304 has a closure, while thefirst and third modules 302, 306 do not have a closure. Where there isno closure, preferably a hard coating is added to the module. Onepreferred coating is diamond-like carbon (DLC).

In the embodiment shown in FIG. 5, the first, second, and third modules302, 304, 306 each have a closure 332, 334, 336, which extends the tapebearing surface of the associated module, thereby effectivelypositioning the read/write elements away from the edge of the tapebearing surface. The closure 332 on the second module 304 can be aceramic closure of a type typically found on tape heads. The closures334, 336 of the first and third modules 302, 306, however, may beshorter than the closure 332 of the second module 304 as measuredparallel to a direction of tape travel over the respective module. Thisenables positioning the modules closer together. One way to produceshorter closures 334, 336 is to lap the standard ceramic closures of thesecond module 304 an additional amount. Another way is to plate ordeposit thin film closures above the elements during thin filmprocessing. For example, a thin film closure of a hard material such asSendust or nickel-iron alloy (e.g., 45/55) can be formed on the module.

With reduced-thickness ceramic or thin film closures 334, 336 or noclosures on the outer modules 302, 306, the write-to-read gap spacingcan be reduced to less than about 1 mm, e.g., about 0.75 mm, or 50% lessthan commonly-used Linear Tape Open (LTO) tape head spacing. The openspace between the modules 302, 304, 306 can still be set toapproximately 0.5 to 0.6 mm, which in some embodiments is ideal forstabilizing tape motion over the second module 304.

Depending on tape tension and tape bending stiffness, it may bedesirable to angle the tape bearing surfaces of the outer modulesrelative to the tape bearing surface of the second module. FIG. 6illustrates an embodiment where the modules 302, 304, 306 are in atangent or nearly tangent (angled) configuration. Particularly, the tapebearing surfaces of the outer modules 302, 306 are about parallel to thetape at the desired wrap angle at the second module 304. In other words,the planes of the tape bearing surfaces 308, 312 of the outer modules302, 306 are oriented at about the desired wrap angle relative to thesecond module 304. The tape will also pop off of the trailing module 306in this embodiment, thereby reducing wear on the elements in thetrailing module 306. These embodiments are particularly useful forwrite-read-write applications. Additional aspects of these embodimentsare similar to those given above.

Typically, the tape wrap angles may be set about midway between theembodiments shown in FIGS. 5 and 6.

Additional aspects of the embodiment shown in FIG. 6 are similar tothose given above.

A 32 channel version of a multi-module head 126 may use cables 350having leads on the same or smaller pitch as current 16 channelpiggyback LTO modules, or alternatively the connections on the modulemay be organ-keyboarded for a 50% reduction in cable span. Over-under,writing pair unshielded cables may be used for the writers, which mayhave integrated servo readers.

The outer wrap angles may be set in the drive, such as by guides of anytype known in the art, such as adjustable rollers, slides, etc. oralternatively by outriggers, which are integral to the head. Forexample, rollers having an offset axis may be used to set the wrapangles. The offset axis creates an orbital arc of rotation, allowingprecise alignment of the wrap angle.

To assemble any of the embodiments described above, conventional u-beamassembly can be used. Accordingly, the mass of the resultant head may bemaintained or even reduced relative to heads of previous generations. Inother approaches, the modules may be constructed as a unitary body.Those skilled in the art, armed with the present teachings, willappreciate that other known methods of manufacturing such heads may beadapted for use in constructing such heads. Moreover, unless otherwisespecified, processes and materials of types known in the art may beadapted for use in various embodiments in conformance with the teachingsherein, as would become apparent to one skilled in the art upon readingthe present disclosure.

Conventionally, limitations on areal density are imposed by loss ofsignal quality due to increase in head-media spacing resulting from headwear, or from deposits or other buildup on the head surface. A methodused by the industry to counter the effects of head wear includespre-recessing and coating the magnetic head. However, pre-recession andcoating increase magnetic spacing between the tape and the surface ofthe sensor and may limit achievable recording linear density.

A longer tape bearing surface between the edges of a module may enableminimal tape-to-head spacing in order to improve resolution and signaloutput. Specifically, a longer tape bearing surface creates a middleregion of the tape bearing surface for the tape to couple with betweenregions of tenting created by the tape at each edge of the module.However, in TMR heads, minimal spacing between tape and the tape bearingsurface of the sensor may result in shorting of the sensor by thepassing tape. Unfortunately, shorting of the TMR sensor has thecapability to render a TMR sensor partially to completelynon-functional.

Particularly, defects in the magnetic medium may cause shorting acrossthe sensor. Conventionally, pre-recessed sensors with very hard coatingson the media bearing surfaces help mitigate wear and shorting due todefects in the magnetic medium passing over the sensor. However, undersevere conditions, such as large defects embedded in the media, shortingmay still occur in these heads. Moreover, coatings may be susceptible towear by the tape and thus become less protective over time.

Methods such as pre-recession of the recording gap and/or coating on thetape bearing surface may also be used to control head-tape spacing.However, neither of these methods enables a way to tailor the spacingaccording to measured head geometry for each head. In addition, when thefabrication processes of the module are complete, there are nopreviously-known methods to make adjustments to the spacing between thehead and tape. Accordingly, because the spacing in conventional headsmay be at a minimal spacing, the shorting problem of TMR sensors hasbeen a pervasive barrier to the introduction of TMR to tape recording.

Various embodiments described herein provide heads having magnetictransducers such as sensors (e.g., data sensors, servo sensors, Halleffect sensors, etc.) and/or write transducers (writer) positioned inthe tape tenting region along the tape bearing surface of the head.Furthermore, positioning the magnetic transducer under the tape tentingregion may enable adjustment of head-to-tape spacing during building ofthe head or when the head is in the drive. Moreover, the tenting of thetape over the magnetic transducer may reduce head-tape friction andout-of-tape fluctuations as well as diminish impact of asperities fromthe tape on the head.

FIGS. 7A-7C illustrate the principles of tape tenting. FIG. 7A shows amodule 700 having an upper tape bearing surface 702 extending betweenopposite edges 704, 706. A stationary tape 708 is shown wrapping aroundthe edges 704, 706. As shown, the bending stiffness of the tape 708lifts the tape off of the tape bearing surface 702. Tape tension tendsto flatten the tape profile, as shown in FIG. 7A. Where tape tension isminimal, the curvature of the tape is more parabolic than shown.

FIG. 7B depicts the tape 708 in motion. The leading edge, i.e., thefirst edge the tape encounters when moving, may serve to skive air fromthe tape, thereby creating a subambient air pressure between the tape708 and the tape bearing surface 702. In FIG. 7B, the leading edge isthe left edge and the right edge is the trailing edge when the tape ismoving left to right. As a result, atmospheric pressure above the tapeurges the tape toward the tape bearing surface 702, thereby creatingtape tenting proximate each of the edges. The tape bending stiffnessresists the effect of the atmospheric pressure, thereby causing the tapetenting proximate both the leading and trailing edges. Modeling predictsthat the two tents are very similar in shape.

FIG. 7C depicts that the subambient pressure urges the tape 708 towardthe tape bearing surface 702 even when a trailing guide 710 ispositioned above the plane of the tape bearing surface.

The heads depicted in the FIGS. discussed above may be constructed tomitigate the occurrence of shorting due to tape defects by inducing tapetenting over the transducers using the teachings presented herein.

While much of the following description refers to a sensor being presentin the tape tenting region, this is done by way of example only, and anytype of transducer may be used in any of the following embodiments inplace of the described sensor.

FIGS. 8A-8F depict an apparatus 800 in accordance with variousembodiments. As an option, the present apparatus 800 may be implementedin conjunction with features from any other embodiment listed herein,such as those described with reference to the other FIGS. Of course,however, such an apparatus 800 and others presented herein may be usedin various applications and/or in permutations which may or may not bespecifically described in the illustrative embodiments listed herein.Further, the apparatus 800 presented herein may be used in any desiredenvironment.

As shown in FIG. 8A, tenting may be induced above the sensitivetransducers, thereby minimizing tape-transducer contact forces in thetenting region. Though the resulting reduced (subambient) air pressurein the area between the tape 802 and the tape bearing surface 808 causesatmospheric pressure to urge the tape towards the tape bearing surface808, the combination of wrap angle, tape bending stiffness andsubambient air pressure under the tape causes the tape 802 to lift fromthe tape bearing surface 808 of the module 801 proximate to the edge 804and return toward tape bearing surface 808, thereby forming the tentingprofile. Subambient air pressure between the tape and tape bearingsurface 808 may be created in any number of ways, such as skiving,active vacuum, presence of wells, air bleed slots, etc.

For present purposes, the wrap angle α is measured between a plane 835of the tape bearing surface 808 and a straight line 823 drawn tangent tothe tape supporting surface of the guide 862 and intersecting the edge804. As shown, the tape tends to bow where it wraps the edge, andconsequently the angle the tape makes relative to the plane 835 of thetape bearing surface 808 at the edge is smaller than the wrap angle α.

Any wrap angle α greater than 0° relative to a plane 835 of the tapebearing surface 808 results in a tent 810 being formed by the movingtape 802 adjacent the edge 804 of the tape bearing surface 808. Thiseffect is a function of the wrap angle, tape bending stiffness, tapesurface roughness, tape surface compressibility, atmospheric pressure,and tape tension, and to a lesser extent, tape speed. For givengeometrical wrap angles, for example, stiffer tapes tend to producelarger tents 810. Nonetheless, where conditions such as wrap angle andtape tension are otherwise identical, tapes of a given type from aparticular manufacturer tend to exhibit a similar tenting profilewhereby the tenting region defined thereunder varies only slightly fromtape to tape. Tapes from different manufacturers and/or generations mayexhibit dissimilar tenting characteristics under otherwise identicalconditions. Fortunately, tenting characteristics are readilydeterminable using numerical modeling techniques known to those of skillin the art, such as Finite Element Modeling (FEM), Finite DifferenceModeling (FDM), etc. and combinations thereof. Nonetheless, differencesin tenting characteristics from tape to tape in the same generationunder otherwise identical conditions may be considered negligible.

In an exemplary embodiment of apparatus 800 as shown in FIG. 8A, amodule 801 has a tape bearing surface 808, an edge 804, and a sensor 809in a thin film region 814 of the module 801. Note that while the presentexemplary embodiment is shown as including a sensor 809, otherembodiments may have a write transducer in place thereof or in additionthereto.

Moreover, module 801 includes a guide 862 positioned relative to theedge 804 for inducing tenting 810 of a moving magnetic recording tape802 passing generally along direction 832. Furthermore, the sensor 809may be positioned under the location of the tenting 810 along a tapetenting region 813 of the tape bearing surface 808. In general, the tapetenting region 813 extends from the edge 804 to a point where the tapeis close to, and then substantially parallels, the tape bearing surface808. In many instances, a midpoint of the tape tenting region 813 isapproximately proximate to the peak 805 of the tenting 810.

In some approaches as illustrated in FIG. 8A, the module 801 may have asensor 809 within the thin film region 814 positioned under the peak 805of the tenting 810. In other approaches, as illustrated in FIG. 8B, themodule 851 may have a sensor 859 within the thin film region 864positioned to the left of the peak 805 of the tenting 810 (for example,proximate to the edge 804) and the edge 804. FIG. 8B also illustrates anembodiment where the sensor 859 is recessed from the plane 835 of thetape bearing surface. Such recession can be applied to any embodimentdescribed herein.

In yet other approaches as illustrated in FIG. 8C, the module 861 mayhave a sensor 869 within the thin film region 874 positioned between thepeak 805 of the tenting 810 and the point of closest approach. Theposition of the sensor is not limited to these examples and may bepositioned at any location under the tenting formed by the motion of themagnetic recording tape.

FIG. 8C also depicts presence of a coating 825 on the media facing sideof the support surfaces 822, 824 and thin film region 874. The runningtape may bevel the edge of the coating, as shown.

Also, as shown in FIG. 8C, at the transition region of the tape betweententing and nontenting, a wear trough 827 may be formed over time by thetape passing thereover. Such wear trough 827 may be formed to someextent during testing at the factory, for example.

The height of the tenting is a function of the wrap angle α at the edge804. Generally, the larger the wrap angle, the more the tape 802 willtend to bend away from the tape bearing surface 808, creating a largertent 810. Ultimately, if the wrap angle α at the edge 804 is high, theforces (atmospheric pressure) urging the tape 802 towards the tapebearing surface 808 may be overcome and the tape 802 then may decouplefrom the tape bearing surface 808 downstream of the tenting 810, inspite of the vacuum. Therefore, the wrap angle α is preferably selectedto provide the desired tenting without breaking the vacuum induced byskiving.

In a preferred embodiment of apparatus 800, the guide 862 may bepositioned to set a wrap angle α of the magnetic recording tape 802relative to a plane 835 of the tape bearing surface 808 that creates thetenting 810 in the moving tape. In other approaches, the tape bearingsurface 808 may be planar.

A guide mechanism 862 may be configured to set a wrap angle α of themagnetic recording tape 802 at edge 804 of the module 801. Such guidemechanisms may include, e.g., a tape guide such as guide 125 of FIG. 1A,a pitch roller, a tension arm, another module, etc. For example, theguide may be a second module having magnetic transducers thereon such asone of the other modules, e.g., as shown in the various FIGS. In furtherapproaches, the guide mechanism 862 may be an outrigger. FIGS. 8D and 8Edepict embodiments having outriggers as guides 862.

Looking to FIG. 8F, different wrap angles α at the edge 804 may be setto create tents 810 a-810 d of different peak heights h. For example, asmaller wrap angle α may create a shallow tent 810 d with the motion ofthe magnetic recording tape 802 over the edge 804, whereas a larger wrapangle (angle not shown, but which may be estimated from the plane 835 ofthe tape bearing surface 808 to the thin line forming a steeper tent 810a) with the motion of the magnetic recording tape 802 over the edge 804.Wrap angles therebetween may cause the moving magnetic recording tape802 to create proportionate tents 810 b, 810 c. In a preferredembodiment of apparatus 800, the wrap angle α created by the guide maybe in a range of about 0.1 to about 1.5 degrees. The peak height h ofthe tenting at this range of wrap angles may range from about 5 nm to 50nm from tape bearing surface 808 to the upper extent of the peak 805 ofthe tenting. For example, a smaller wrap angle may create a peak heighth of about 5 nm of the tenting 810 d as illustrated in FIG. 8F. Thus, bycontrolling the degree of the wrap angle, the head-to-tape spacing abovethe sensor may be controlled.

Multiple modules may be assembled to form a tape head having an internalwrap angle that may be selected based on a measurement of theedge-to-sensor separation for each module.

In the embodiment of apparatus 800 as shown in FIG. 8A, the module 801includes a tape support surface 822 on one side of the thin film region814 and a tape support surface 824 on an opposite side of the thin filmregion 814, where an outer edge of tape support surface 822 may be askiving edge 804 depending on the direction of tape motion.

Looking to FIG. 8A-8B, the module 801 preferably includes a thin filmregion 814 and a CPP sensor 809 (e.g. such as a TMR sensor, GMR sensor,etc. of a type known in the art) that are positioned between the tapesupport surfaces 822, 824.

According to some embodiments, the sensor 809 may be configured as adata sensor for reading data tracks of a magnetic medium. In someapproaches, the apparatus 800 includes one or more arrays of such datasensors.

According to some embodiments, the sensor 809 may be configured as aservo pattern reading sensor of a servo reader. For example, the sensor809 may be configured as a servo pattern reading sensor where apparatus800 includes one or more arrays of data sensors and/or writers and oneor more servo pattern reading sensors for reading servo data on amedium.

In yet another embodiment, a module is comprised of an array of writertransducers and servo readers. In this case, the servo readers may beused for sensing and/or for setting the magnetic spacing in the tent.

One embodiment of apparatus 800 may include a drive mechanism such as amotor or other known mechanism that is configured to cause the tape tomove over the module and a controller electrically coupled to the drivemechanism. For example, the motor or other known mechanism may drive atape supply cartridge, e.g., tape supply cartridge 120 of FIG. 1A, and atake-up reel, e.g., take-up reel 121 also of FIG. 1A, of a drive inwhich the block is implemented in, to move the tape media over themodule and/or other components of the drive.

FIG. 9 depicts an apparatus 900 in accordance with one embodiment. As anoption, the present apparatus 900 may be implemented in conjunction withfeatures from any other embodiment listed herein, such as thosedescribed with reference to the other FIGS. Of course, however, such anapparatus 900 and others presented herein may be used in variousapplications and/or in permutations which may or may not be specificallydescribed in the illustrative embodiments listed herein. Further, theapparatus 900 presented herein may be used in any desired environment.

Referring to FIG. 9, the components are similar to those of FIG. 8A, andtherefore have common numbering. However, the magnetic transducer 809,e.g., writer and/or sensor is positioned toward an edge of the tapetenting region 813 at about a point of closest approach 902 of the tape802 and the tape bearing surface 808. Any of the aforementioned featuresmay be used in conjunction with this embodiment.

The present invention may be a system, a method, and/or a computerprogram product. The computer program product may include a computerreadable storage medium (or media) having computer readable programinstructions thereon for causing a processor to carry out aspects of thepresent invention.

The computer readable storage medium can be a tangible device that canretain and store instructions for use by an instruction executiondevice. The computer readable storage medium may be, for example, but isnot limited to, an electronic storage device, a magnetic storage device,an optical storage device, an electromagnetic storage device, asemiconductor storage device, or any suitable combination of theforegoing. A non-exhaustive list of more specific examples of thecomputer readable storage medium includes the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a static random access memory (SRAM), a portablecompact disc read-only memory (CD-ROM), a digital versatile disk (DVD),a memory stick, a floppy disk, a mechanically encoded device such aspunch-cards or raised structures in a groove having instructionsrecorded thereon, and any suitable combination of the foregoing. Acomputer readable storage medium, as used herein, is not to be construedas being transitory signals per se, such as radio waves or other freelypropagating electromagnetic waves, electromagnetic waves propagatingthrough a waveguide or other transmission media (e.g., light pulsespassing through a fiber-optic cable), or electrical signals transmittedthrough a wire.

Computer readable program instructions described herein can bedownloaded to respective computing/processing devices from a computerreadable storage medium or to an external computer or external storagedevice via a network, for example, the Internet, a local area network, awide area network and/or a wireless network. The network may comprisecopper transmission cables, optical transmission fibers, wirelesstransmission, routers, firewalls, switches, gateway computers and/oredge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device.

Computer readable program instructions for carrying out operations ofthe present invention may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, or either source code or object code written in anycombination of one or more programming languages, including an objectoriented programming language such as Smalltalk, C++ or the like, andconventional procedural programming languages, such as the “C”programming language or similar programming languages. The computerreadable program instructions may execute entirely on the user'scomputer, partly on the user's computer, as a stand-alone softwarepackage, partly on the user's computer and partly on a remote computeror entirely on the remote computer or server. In the latter scenario,the remote computer may be connected to the user's computer through anytype of network, including a local area network (LAN) or a wide areanetwork (WAN), or the connection may be made to an external computer(for example, through the Internet using an Internet Service Provider).In some embodiments, electronic circuitry including, for example,programmable logic circuitry, field-programmable gate arrays (FPGA), orprogrammable logic arrays (PLA) may execute the computer readableprogram instructions by utilizing state information of the computerreadable program instructions to personalize the electronic circuitry,in order to perform aspects of the present invention.

Aspects of the present invention are described herein with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems), and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer readable program instructions.

These computer readable program instructions may be provided to aprocessor of a general purpose computer, special purpose computer, orother programmable data processing apparatus to produce a machine, suchthat the instructions, which execute via the processor of the computeror other programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks. These computer readable program instructionsmay also be stored in a computer readable storage medium that can directa computer, a programmable data processing apparatus, and/or otherdevices to function in a particular manner, such that the computerreadable storage medium having instructions stored therein comprises anarticle of manufacture including instructions which implement aspects ofthe function/act specified in the flowchart and/or block diagram blockor blocks.

The computer readable program instructions may also be loaded onto acomputer, other programmable data processing apparatus, or other deviceto cause a series of operational steps to be performed on the computer,other programmable apparatus or other device to produce a computerimplemented process, such that the instructions which execute on thecomputer, other programmable apparatus, or other device implement thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof instructions, which comprises one or more executable instructions forimplementing the specified logical function(s). In some alternativeimplementations, the functions noted in the block may occur out of theorder noted in the figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts or carry out combinations of special purpose hardwareand computer instructions.

Moreover, a system according to various embodiments may include aprocessor and logic integrated with and/or executable by the processor,the logic being configured to perform one or more of the process stepsrecited herein. By integrated with, what is meant is that the processorhas logic embedded therewith as hardware logic, such as an applicationspecific integrated circuit (ASIC), a field programmable gate array(FPGA), etc. By executable by the processor, what is meant is that thelogic is hardware logic; software logic such as firmware, part of anoperating system, part of an application program; etc., or somecombination of hardware and software logic that is accessible by theprocessor and configured to cause the processor to perform somefunctionality upon execution by the processor. Software logic may bestored on local and/or remote memory of any memory type, as known in theart. Any processor known in the art may be used, such as a softwareprocessor module and/or a hardware processor such as an ASIC, a FPGA, acentral processing unit (CPU), an integrated circuit (IC), etc.

It will be clear that the various features of the foregoing systemsand/or methodologies may be combined in any way, creating a plurality ofcombinations from the descriptions presented above.

It will be further appreciated that embodiments of the present inventionmay be provided in the form of a service deployed on behalf of acustomer.

The inventive concepts disclosed herein have been presented by way ofexample to illustrate the myriad features thereof in a plurality ofillustrative scenarios, embodiments, and/or implementations. It shouldbe appreciated that the concepts generally disclosed are to beconsidered as modular, and may be implemented in any combination,permutation, or synthesis thereof. In addition, any modification,alteration, or equivalent of the presently disclosed features,functions, and concepts that would be appreciated by a person havingordinary skill in the art upon reading the instant descriptions shouldalso be considered within the scope of this disclosure.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example only, and notlimitation. Thus, the breadth and scope of an embodiment of the presentinvention should not be limited by any of the above-described exemplaryembodiments, but should be defined only in accordance with the followingclaims and their equivalents.

What is claimed is:
 1. An apparatus, comprising: a module having a tapebearing surface, a magnetic transducer in a thin film region, and anedge closest thereto; and a guide positioned relative to the edge forinducing tenting of a moving magnetic recording tape above a tapetenting region of the tape bearing surface, wherein the magnetictransducer is positioned along the tape tenting region, wherein themagnetic transducer is positioned in the tape tenting region between apeak of the tenting of the moving magnetic recording tape and the edge,wherein the magnetic transducer is positioned a distance from a locationon the tape bearing surface directly under the peak that is more thanone-fourth the length from the location directly under the peak to theedge closest thereto.
 2. An apparatus as recited in claim 1, wherein theguide is positioned to set a wrap angle relative to a plane of the tapebearing surface, the wrap angle being greater than 0 degrees.
 3. Anapparatus as recited in claim 2, wherein the wrap angle is in a range ofabout 0.1 to about 1.5 degrees.
 4. An apparatus as recited in claim 1,wherein the tape bearing surface is planar.
 5. An apparatus as recitedin claim 1, wherein a media facing side of the magnetic transducer isrecessed from the tape bearing surface.
 6. An apparatus as recited inclaim 1, comprising a wear coating on the tape bearing surface.
 7. Anapparatus as recited in claim 1, wherein the guide is a roller.
 8. Anapparatus as recited in claim 1, wherein the guide is a second modulehaving magnetic transducers thereon.
 9. An apparatus as recited in claim1, wherein the guide is an integral outrigger.
 10. An apparatus asrecited in claim 1, wherein the magnetic transducer is a tunnelingmagnetoresistance sensor.
 11. An apparatus as recited in claim 1,wherein the magnetic transducer is a write transducer.
 12. An apparatusas recited in claim 11, wherein the write transducer is not recessed.13. An apparatus as recited in claim 1, wherein the magnetic transduceris a Hall effect sensor.
 14. An apparatus as recited in claim 1, furthercomprising: a drive mechanism for passing a magnetic medium over themodule; and a controller electrically coupled to the magnetictransducer.
 15. An apparatus, comprising: a module having a tape bearingsurface, an array of magnetic transducers in a thin film region, and anedge closest thereto; and a guide positioned relative to the edge forinducing tenting of a moving magnetic recording tape above a tapetenting region of the tape bearing surface, wherein the magnetictransducers are positioned along the tape tenting region, whereinmagnetic transducers are positioned in the tape tenting region between apeak of the tenting of the moving magnetic recording tape and the edge,wherein the magnetic transducers are positioned a distance from alocation on the tape bearing surface directly under the peak that ismore than one-fourth the length from the location directly under thepeak to the edge closest thereto.
 16. An apparatus as recited in claim15, wherein the guide is positioned to set a wrap angle relative to aplane of the tape bearing surface, the wrap angle being greater than 0degrees.
 17. An apparatus as recited in claim 16, wherein the wrap angleis in a range of about 0.1 to about 1.5 degrees.
 18. An apparatus asrecited in claim 15, wherein the tape bearing surface is planar.
 19. Anapparatus as recited in claim 15, wherein media facing sides of themagnetic transducers are recessed from the tape bearing surface.
 20. Anapparatus as recited in claim 15, comprising a wear coating on the tapebearing surface.
 21. An apparatus as recited in claim 15, furthercomprising: a drive mechanism for passing a magnetic medium over themodule; and a controller electrically coupled to the magnetictransducers.
 22. A method, comprising: positioning a guide relative toan edge of a substrate of a module having a tape bearing surface, amagnetic transducer in a thin film region, and the edge closest thereto;and running a moving magnetic recording tape above the tape bearingsurface for inducing tenting of the moving magnetic recording tape abovea tape tenting region of the tape bearing surface of the substrate,wherein the magnetic transducer is positioned in the tape tenting regionbetween a peak of the tenting of the moving magnetic recording tape andthe edge, wherein the magnetic transducer is positioned a distance froma location on the tape bearing surface directly under the peak that ismore than one-fourth the length from the location directly under thepeak to the edge closest thereto.
 23. The method as recited in claim 22,wherein the guide is positioned to set a wrap angle relative to a planeof the tape bearing surface, the wrap angle being greater than 0degrees.
 24. The method as recited in claim 23, wherein the wrap angleis in a range of about 0.1 to about 1.5 degrees.
 25. The method asrecited in claim 22, wherein the magnetic transducer is a tunnelingmagnetoresistance sensor.